It seems you're prepared and well-more prepared than most people. It's not difficult to do right? I think it also becomes more of a focus once one starts the process.

Communication is a difficult thing and most consumer-available comms devices will not span distances. Ham radio will be your best bet but training and licensing is required; for sure it's a good option though. People seem to think their mobile phone is enough but that's not true. A Satellite phone is a good option, one at your end and one at hers, but even then that relies on a satellite and they can be costly.

May it never come to pass, but may you continue to be prepared for when/if it does.